Sheet materials are widely available for wrapping the exterior surfaces of buildings prior to the attachment of siding materials. Housewraps, as they are called in the trade, restrict the passage of rain water and ambient air from entering the interior of a building, permit water vapor to escape and help to contain “conditioned” air in the interior of the structure.
Some housewraps that are currently in the marketplace include TYVEC®, a high density polyethylene spun-bonded sheet material from duPont Company, Wilmington, Del., TYPAR housewrap, spun-bonded polypropylene fiber mat material from Reemeay, Inc., Old Hickory, Tenn. and RUFCO-WRAP, a microperforated polyethylene sheet material sold by Raven Industries, Inc., Sioux Falls, S.D.
More recently, laminated barrier strips have been available to effectively reduce air and water leakage at gaps and joints in sheathing material. One such product is THERMO-BRITE tapes available through Parsec, Incorporated, Dallas, Tex. Such tapes are specially designed with pressure-sensitive adhesive strips and paper release backing layers for easy application at a job site. The tapes can be applied to sheathing joints, sheathing damage, window and door openings, electrical conduits and plumbing lines, for example. They are typically provided in two inch or four inch widths. Like housewrap material, such tapes resist the penetration of liquid water and reduce air leakage. Such products have recently been reported in U.S. Pat. No. 5,374,477 dated Dec. 20, 1994 and European Patent Application No. 399,952 published on Nov. 28, 1990.
While these adhesive-backed barrier strips and housewraps provide a breathable water barrier for joints and gaps between structural members of a building, they are typically manufactured from rather expensive polymeric sheet or foam materials which incorporate minute passageways between their major surfaces for permitting the passage of water vapor while restricting the passage of liquid water and air. Such specially-made polymeric materials are tough and resilient but do not retain nails very well, and are not flame retardant.
Breathable, liquid water retardant fabrics have also been used in soft structures where drape, hand and soft feel are of prime importance, such as in limited-use protective garments. TYVEC® from duPont has been used in protective garments and work-wear as well as in hazardous environments and other industrial uses. Such garments may be uncomfortable to wear for extended periods of time in warm conditions, and they are also not very durable, especially when wet laundered. Goretex® Teflon® fabric has also been used in garments, such as outerwear, with much success. Although Goretex® fabric is launderable, it is quite expensive.
Finally if a breathable, more cost-effective, water retardant fabric was available, many other uses could be economically pursued. For example, batt insulation and duct liner could be manufactured with such a facing. Additionally, envelopes could be made on a more cost-effective basis than those presently made with TYVEC® material.
Accordingly, there is a need for a composite sheet material that acts as a barrier to fluids, yet is also highly permeable to moisture vapor, with improved mechanical properties such as greater nail holding ability, better flame spread resistance, and more cost efficiencies for multiple uses.